Packaging film of polyolefin or the like, for packaging a medicine or a drug substance thereof, is sometimes required to conform to a country-specific pharmacopeia, such as Japanese Pharmacopeia or European Pharmacopeia, in producing a medical drug. Close attention has been paid to prevent a medicine or a drug substance thereof from contamination caused by a bleed-out and incorporation of impurities inside of a packaging film, or caused by an incorporation of dust electrostatically adsorbed on the surface of a packaging film.
At the present time, in a drug substance manufacturer of a medicine and in a pharmaceutical manufacturer, use can be made of; a sheet-shape packaging film formed of a resin having added thereto a surfactant that does not affect components of a medicine, in order to prevent contamination during transportation between factories or during transfer between processes inside a factory; a sheet-shape packaging film formed of a resin free of a surfactant for avoiding bleed-out: or a bag-shape packaging film formed by those.
The sheet-shape or bag-shape packaging films have various sizes such as a size for packaging a drug substance powder of several 100 g unit, a size for packaging a bag for packaging a drug substance powder and accommodating it in a drum can, and a size for packaging a drug substance powder of at most about 200 kg.
A drug substance of a medicine is mainly a granular powder. In a sheet-shape or bag-shape packaging film made of a resin to which no antistatic function is imparted, there is a possibility that an accident of dust explosion occurs. Therefore, a packaging film having added thereto additives described in a positive list related to foodstuffs or a packaging film having an antistatic function conforming to a country-specific pharmacopeia including Japanese Pharmacopeia, is sometimes required.
A packaging film formed of a resin having added thereto a surfactant to impart an antistatic function has been known. However, humidity affects the surfactant to exhibit an antistatic function, and the antistatic function may be deteriorated in a low humidity environment. Furthermore, bleed-out or elution of the surfactant may adversely affect a medical drug to be packaged or the antistatic function may be deteriorated with the lapse of time. For these reasons, a packaging film formed of a resin having added thereto a polymer antistatic agent is preferably used in order to eliminate those demerits of the surfactant.
Antistatic film containing a potassium ionomer as such a polymer antistatic agent has been known. In the case where the antistatic film is a multilayer film using a potassium ionomer and has an ionomer-containing layer as the innermost layer in contact with contents, the amount of a water-elutable alkali component is increased and thus, the antistatic film does not conform to a country-specific pharmacopeia including European Pharmacopeia.
As an antistatic film that is a multilayer film using a potassium ionomer and has an ionomer-containing layer in an inner layer that is not in direct contact with contents, Patent Literature 1 discloses a dust-proof laminate containing at least three layers in which at least one layer of surface layers is a thermoplastic resin layer, in which the laminate contains a non-electrostatically chargeable layer, containing (A) a thermoplastic resin, (B) a potassium ionomer of an ethylene-unsaturated carboxylic acid copolymer and (C) a polyhydroxyl compound, and provided in an intermediate layer adjacent to the thermoplastic layer.
Patent Literature 2 discloses a laminate having at least three layers, in which both surface layers thereof are constituted of a polymeric material having a surface resistivity of 1×1014Ω or more, an intermediate layer is constituted of a potassium ionomer of an ethylene-unsaturated carboxylic acid copolymer or of a mixture of the potassium ionomer and a thermoplastic monomer, and at least one layer of the surface layers has a 10% attenuation time of 20 seconds or less at an applied voltage of +5,000V measured in the atmosphere of 2.3° C. and a relative humidity of 50%.
Patent Literatures 1 and 2 do not show that these laminates can be applied to a medicine packaging and do not show specific component, constituents and adjustment of layer constituent components for achieving the application. Furthermore, in the case of having an ionomer-containing layer as an intermediate layer, there is no known laminate conforming to a country-specific pharmacopeia including European Pharmacopeia, even though a thickness of an innermost, layer or an inner layer is controlled, the amount of a potassium ionomer is adjusted and components are selected.